Electronic – Building custom hardware for programming boards with microcontrollers

A debug LED (You can convert it into a watchdog blinky later to verify that your main loop/1ms interrupt or whatever you're using is still running) is something that I would consider pretty mandatory for an exploratory board. Hello World on your new PCB does not need to be as complex as an LCD. You could repurpose a backlight controlling MOSFET for this purpose if you don't want to add the real components.

I'm assuming you're giving yourself some form of breakout for your extra pins - An LCD screen is great, and I understand the desire to keep it simple, but there's little that can go wrong simply by adding a trace to nowhere, and nowhere can become somewhere someday. Even if you don't want to add real headers, some test points (in the form of staggered rows of .05x.1" copper pads) will let you solder and hot glue some wires on later. This doesn't have to be a big deal. I'd put some jumpers/resistors on those lines, so you can add some 1k resistors to protect your pins from being shorted or hit with ESD if you decide to do so. This also gives you the ability to pull any of your other pins high or low if later you find this is necessary!

One thing that I do on a first board is add a lot of vias. Vias are your friends when making modifications (assuming you're getting this done at a PCB house and don't have to drill them yourself). If you've got two vias on every trace, even if you don't change sides with your trace, you can cut the trace later with an Xacto and run 30-ga wire wrap wire between the traces that need to be swapped (Make sure your vias are big enough for this, though). You can also add 0805 0-ohm jumpers (solder bridges are cheap; you don't need to buy components) and solder wires to the pads later if you don't like the via method. Probably won't be necessary, but it's cheap/free insurance.

Oh, and connect the LCD/USB setup first, then tack wires on temporarily from your working breadboard to make sure that the externals are working.

One reason why the Launchpad is so cheap is because the chip it uses is a very low-end device, which is missing many useful peripherals such as a UART. You will find things much easier if you use one of the other, more capable, devices You will need a FET, of course, but they aren't all that expensive, and it is a very useful tool.

Pins 16 and 17 on the target device are used for debugging. It might be possible to use them in your application if they are isolated with resistors, Microchip recommends that solution for debugging their devices when the ICSP pins are in use.

Most people build software like that starting from a simple application using one peripheral, and then add the additional functionality to the same program. Combining programs can cause problems.

A useful resource for MSP430 development is this Yahoo MSP430 group.